Olefin hydroformylation is one of the important methods for synthesizing aldehydes and alcohols, and the like industrially. Currently, over 10 million tons of aldehydes and alcohols are produced by the olefin hydroformylation technique annually in the world. This reaction can produce aldehydes from olefins under less severe conditions, and further, the product aldehydes can be converted to alcohols by hydrogenation. Homogeneous catalytic systems exhibit a relatively high catalytic activity and a target product selectivity under relatively mild reaction conditions, but the separation of the catalyst from the reaction materials is difficult. As compared with homogeneous catalysis, the most important advantage of heterogeneous catalysis is that it is easy to separate the catalyst from the reaction materials, with the main problems of severe reaction conditions, a relatively low reactivity, and the like. At present, the main research hotspot of hydroformylation focuses on developing a novel heterogenized catalyst so that it not only has the advantage of heterogeneous catalysis, being easy to separate the catalyst from the reaction materials, but also exhibits a high reactivity and mild reaction conditions of homogeneous catalysis.
Kausik Mukhopadhyay et al (Chem Mater, 2003, 15:1766-1777) performed passivation treatment to the outer surface of the molecular sieves MCM-41 and MCM-48 with diphenyldichlorosilane, and then modified the inner surface of the molecular sieves with 3-aminopropyltrimethoxysilane, so that HRh(CO)(PPh3)3 can be selectively immobilized on the inner surface of the molecular sieves. The most notable highlight is that the authors selectively immobilized HRh(CO)(PPh3)3 on the inner surface of the molecular sieves MCM-41 and MCM-48 inventively. However, this heterogeneous catalytic system has a relatively low reactivity in view of the reaction effect of catalyst, and the results of recycle show that the recyclability of the catalyst is relatively poor and the loss of metal is relatively serious.
Bassam El Ali et al (Journal of Molecular Catalysis A: Chemical, 2006, 250:153-162) immobilized a heteropolyacid on a MCM-41 support, while immobilizing HRh(CO)(PPh3)3 on the MCM-41 support. The research showed that the presence of the heteropolyacid can not only improve the reactivity of hydroformylation, but also effectively reduce the problem of metal loss, so as to ensure the stability of the reaction of the heterogeneous catalyst.
N. Sudheesh et al (Journal of Molecular Catalysis A: Chemical, 2008, 296:61-70) encapsulated the HRh(CO)(PPh3)3 catalyst in situ in the HMS mesoporous molecular sieve, and applied it to hydroformylation reactions of long chain olefins. The authors took the reaction of 1-hexene in slurry bed as the focal point of research, and discussed the effects of the temperature, the partial pressure of carbon monoxide, the partial pressure of hydrogen, the amount of catalyst, and the like, on the reactivity, and the results of recycle of catalyst show that the catalyst has a relatively good recyclability. Thereafter, N. Sudheesh et at (Applied Catalysis A: General, 2012, 415-416:124-131) applied the catalytic system to the hydroformylation reaction of propylene, in which HRh(CO)(PPh3)3 is encapsulated in situ in the HMS mesoporous molecular sieve. As a nanoscale reactor, the HMS mesoporous molecular sieve exhibits a relatively high stability in research of recycle. However, there is still a relatively large difference in reactivity, as compared with homogeneous catalytic systems.
Ki-Chang Song et at (Catalysis Today, 2011, 164:561-565) subjected SBA-15 to post-modification by two methods. One method is a passivation treatment to the outer surface of SBA-15 with diphenyldiethoxysilane, and then modification to the inner surface of SBA-15 with N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, so as to achieve the purpose of immobilizing Rh4(CO)12 to SBA-15 by reacting Rh4(CO)12 with the amino group in the modified inner surface. The other method is modification to the surfaces of SBA-15 with N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane directly, so as to achieve the purpose of immobilizing Rh4(CO)12 to SBA-15 by reacting Rh4(CO)12 with the amino group in the modified outer/inner surface of the molecular sieve. The research shows that the immobilized catalyst formed by the second treatment method exhibits more excellent activity and stability in hydroformylation reactions. The authors explained the reason why the catalyst has a better activity lies in the simultaneous modification to the inner and outer surfaces, which can allow Rh4(CO)12 to be dispersed more uniformly in the inner and outer surfaces of the molecular, so that the homogeneous catalyst has a larger free space. The authors' research shows that the normal/isomeric ratio (n/i) is relatively high because of the steric hindrance effect of the ligand, which facilitates the generation of linear aldehydes.
Hanh Nguyen Thi Ha et at (Catalysis Communications, 2012, 25:136-141) produced a supported ionic liquid heterogeneous catalyst from Rh(acac)(CO)2 and a ligand TPPTS, and applied it to the hydroformylation reaction of ethylene. The authors researched the effects of the amount of the ionic liquid, the reaction temperature, the pressure, and the like, on the catalytic activity. The research shows that a high amount of the ionic liquid is disadvantageous for the reactivity of hydroformylation. The Characterizations performed by FTIR, SEM, and EDX analysis, and the like, indicate that the reason for the deactivation under a relatively high amount of the ionic liquid is that the ionic liquid overflows from the pores of the support, resulting in the loss of the homogeneous catalyst, and thus the notable decrease of the reactivity.
The researches mentioned above are classified into two methods. One method is pre-modification to the support to make the support have a corresponding organic functional group, and then immobilization of the homogeneous catalyst on the support by the chemical reaction between the catalyst, such as homogeneous HRh(CO)(PPh3)3, and the organic functional group. The other method is in situ addition of the catalyst, such as homogeneous HRh(CO)(PPh3)3, during the synthesis of the support, enabling the interaction between the homogeneous catalyst and the organic functional group, so that the homogenous catalyst is formed in the support, while the support is synthesized. The general concept of the two methods mentioned above is the reaction of an organic functional group with a homogeneous catalyst, so as to immobilize the homogeneous catalyst on a heterogeneous support. The significant problems in these two methods are the loss of the homogeneous catalyst, and the decrease of the reactivity of the homogeneous catalyst when being immobilized on the support. These two problems are the primary bottlenecks which restrict the homogeneous immobilization for hydroformylation.
Balue et at (J. Mol. Catal. A: Chem., 1999, 137: 193-203) used a cation exchange resin as the support, and prepared a heterogeneous catalyst by immobilizing a rhodium-sulfur compound. However, the heterogeneous catalyst exhibits poor stability and relatively serious Rh loss phenomenon, as shown by the recycle experiment of styrene hydroformylation. Zeelie et at (Appl. Catal. A: Gen, 2005, 285: 96-109) modified polyethylene fibers with styrene and p-styrenediphenylphosphine, then anchored Rh(acac)(CO)2 onto the modified polyethylene fibers, and the results of ethylene hydroformylation show that the catalyst provides a relatively high conversion but a poor stability at 100° C. and 5 bar, and that after 50 h, the reactivity rapidly decreases and the deactivation phenomenon of the catalyst is relatively serious. Ricken et at (J. Mol. Catal. A: Chem, 2006, 257: 78-88) modified the ligand NIXANTPHOS by various functionalization, and co-supported the modified ligand and Rh(acac)(CO)2 on polyglycerol compound, and the results of 1-octene hydroformylation show that the catalyst provides a conversion up to about 90% at 80° C. and 20 bar. However, the industrial application of this catalyst is greatly limited, because the polymeric supports purchased commercially or produced by normal radical polymerization of styrene show the following problems: the formation of gel, swelling of the polymer, limited loading amount of the phosphorus ligand in the framework of the polymer, loss of the component having catalytic activity, and the like.
U.S. Pat. No. 4,252,678 discloses the production of a colloidal dispersion containing a transition metal, such as Rh, etc, in which the catalyst system is consisted of a transition metal component in form of a colloidal dispersion of 1.0 to 20.0 nm and (styrene/butadiene) functionalized copolymer terminated with a hydroxy group, and is used in the hydroformylation reaction of 1-octene. The catalyst prepared by this method cannot be used in fixed bed reactors and trickle bed reactors, and it is difficult to separate the catalyst from the product.
CN 102281948 A reports a polymer-supported transition metal catalyst complex and method for use, and produces a soluble polymer-supported rhodium catalyst having a narrow molecular weight distribution. However, all the processes for production of the catalyst, the catalytic reaction, and the separation of the catalyst are complicated. In the production of the catalyst, it is required to synthesize a soluble polymer by controlling functional monomers and styrene, etc., and then introduce a ligand, and at last support the Rh catalyst. It is required to add compressed gas during the catalytic reaction. The catalyst is separated from the reaction mixture by means of nanofiltration, and the reaction results are not ideal, either.
The paper “Study on the Suzuki Coupling Reaction Catalyzed by Palladium Catalyst supported in Microcapsule Film” (Kaixiao LI, CMFD, No. 8) reports that a Pd-based catalyst is produced by using a microcapsule material as the support, which is connected with a phosphorus ligand in the polystyrene microcapsule film, and used in Suzuki coupling reaction. However, the microcapsule material is a copolymer material, rather than a monopolymer material. The dispersion state of the transition metal component in this catalyst is not mentioned.